Color kinescope adjunct



Dec. 9, 1958 A. G. LAZZERY 2,864,021

COLOR KINESCOPE ADJUNCT Filed Sept. 1, 1955 2 Sheets-Sheet l IN VEN TOR.-0 6. ZAZZEK) irrmwsr Dec. 9, 1958 A. G. LAZZERY 2,864,021

COLOR KINESCOPE ADJUNCT Filed Sept. 1, 1955 2 Sheets-Sheet 2 INVIJNTOR.A/vazw ZAZZZWY /7 r ra/ewar COLOR KENESCOFE ADEUNCT Angelo G. Lazzery,Oaklyn, N. l, assignor to Radio Corporation of America, a corporation ofDelaware Application September 1, M55, Serial No. 531,344)

6 Claims. (Ci. 3l3--77) The present invention relates to apparatus forcontrolling the electron beams of cathode ray'tubes and, particularly,to electromagnetic convergence apparatus for use in arrangements inwhich a plurality of beam components is deflected by a common deflectionapparatus.

One type of cathode ray tube with which the present invention may beadvantageously employed is a color kinescope of the general typedescribed in an article entitled Deveiopment of a 21-inch Metal EnvelopeColor Kinescope by Seelen et al. which appeared in the March 1955 issueof RCA Review. Such a tube has a luminescent screen as part of a targetstructure in which different phosphor areas produce different coloredlight when excited by electron beam components impinging upon it fromdifferent angles, the angle of impingement determining the particularcolor of the light produced by the screen. The invention also pertains,for example, to a kinescope of the type described in an article entitledA One-Gun Shadow-Mask Color Kinescope by R. R. Law, published in theProceedings of the l. R. E., October 1951, at page 1194. It is necessaryfor the satisfactory operation of such kinescopes to effect substantialconvergence of the electron beam components at all points of the rasterscanned thereby at the target electrode.

In general, such convergence may be eitected by means of apparatuscomprising means for producing a plurality of electron beam componentswhich traverse predefiection paths which are spaced respectively aboutthe longitudinal axis of the tube and individual electron magnetic meanslocated respectively adjacent to the predefle-ction beam paths. Theelectromagnetic means are of such character as to be energized directlyfrom the beam deflection circuitry in a manner to effect the desiredbeam convergence. Such convergence apparatus is described andillustrated in an article entitled Deflection and Convergence of the21-inch Color Kinescope which appeared in the same issue of the RCAReview cited above. This type of convergence apparatus is also describedin the Seelen et al. article.

In the 21 AX? 22 color kinescope described by Seelen et al., three pairsof radially and inwardly extending pole pieces are provided internallyof the kinescope neck. Each pair of pole pieces is thus adapted, whenexcited by external magnets, to control one of the electron beams forthe purpose of effecting the requisite convergence of the beams to thetarget electrode. One problem which has heretofore existed is that whichis concerned with the neck mounting means for securing the externalmagnets about the tube in proper relation to their associated internalpole pieces.

it is, therefore, a primary object of the present invention to provide anew and improved convergence magnet assembly for use with a colorkinescope of "the type described.

V aration, it is necessary that the external magnet pole.

By reason of the fact that the electron guns which produce the severalelectron beams in such a kinescope 1 Patented Dec. 9, 1958 and theinternal pole pieces which operate upon the beams in the convergencefunction are equi-angularly displaced from each other, the externalmagnets must also be equi-angularly displaced in order for the externalmagnets to operate properly with the internal pole pieces. One featurewhich complicates the structure of the convergence magnet assembly isthat the diameter of the tube neck varies from tube to tube within thelimits of, for example, Thus, the external convergence magnet assemblymust be capable of adapting itself to tube necks of various sizes. Inaddition to the requirement that the external magnets retain theirequi-angular seppieces remain substantially perpendicular to thelongitudinal axis of the kinescope, in concentric relation thereto, andthat all of the external magnets be perpendicular to the kinescope axis.

Thus, it is a more specific object of the present invention top providea convergence magnet assembly meeting the foregoing requirements throughthe agency of relatively simple mechanical apparatus.

In general, the present invention comprises a plurality of foot members,one for each of the external magnets, arranged to form the sides of anequilateral polygon. Each foot member is provided at its ends with meansfor slidably engaging the ends of adjacent foot members, the slidingengagement being of such character that the foot members are capable ofmoving only radially with respect to a circle circumscribed by them.

Each of the external convergence magnets, in accordance with one form ofthe invention, includes a pair of L.-shaped magnetic pole pieces whichcooperate with the above-describedinternal pole pieces of the kinescope.Novel means are provided by the present invention for preventing theL-shaped pole pieces from abrading the kinesco-pe neck while maintainingthe external pole pieces sufiiciently close to the neck of the kinescopeto meet electrical requirements. Spring means secure the plurality offoot members in their polygonal relationship and permit expansion andcontraction of the assembled foot members to accommodate variouskinescope neck diameters. Such expansion and contraction is, moreover,effected without affecting undesirably the angular relationship betweenthe magnets, the perpendicularity of the magnets to the longitudinalaxis or the concentricity of the assembly.

Additional objects and advantages of the present invention will becomeapparent to those skilled in the art from a study of the followingdetailed description of the accompanying drawing, in which:

Figure 1 is a side-elevational view of a kinescope provided with aconvergence magnet assembly in accordance with the present invention;

Figure 2 is an elevational view, partially in section, of a convergencemagnet assembly according to one form of the invention;

Figure 3 is an exploded, isometric view of a portion of the apparatus ofFigure 2, with coils omitted in the interest of clarity;

Figure 4 is an isometric view of one of the magnets of Figure 2, withcoils omitted:

Figures 5 and 6 are enlarged fragmentary views of portions of theapparatus of Figure 2; and

Figure 7 is an elevational view, partially in section, of another formof the invention.

Reference will first be made to Figure l for a general description of anillustrative embodiment of an electron beam convergence in accordancewith the present invention. The system includes a tri-color kinescope 10which may be ofthe same type as that disclosed in the abovecited Seelenet al. article. It will be understood, ho. ever, that the kinescope may,alternatively, be of other ranged in groups and capable, respectively,of producing light of the ditferent component colors in which the imageis to be reproduced. In back of and spaced from the screen 12 is anaperture masking electrode 14 having an aperture for and in alignmentwith each group of phos-.

phor areas of the screen.

In the particular tube illustrated, the kinescope also has a pluralityof electron guns (not shown), equal in number to the number of primarycolors in which the image is to be reproduced. The electron guns, threein number, for example, produce the schematically represented electronbeams 17, 18 and 19 by which to energize, respec-- tively, the blue, redand green phosphor areas of the screen 12. When these three electronbeams are properly converged at the masking electrode 14 they passthrough the apertures thereof from different directions and impinge upondifierent phosphor areas of the various groups so as to produce blue,red and green light. It is to be noted that the size of the phosphorareas, the angles between the beams and the spacing of the mask 14 fromthe screen 12 as compared with the length of the tube shown areexaggerated for better illustration of the operation of the kinescope.

The details of the construction of such a tube are given in theSeelen etal. article and also in the article by R. R. Law entitled A Three-GunShadow-Mask Kinescope" published in the October 1951 issue ofProceedings of the I. R. E. It may be noted that the electron beams 17,18 and 19 are suitably modulated in intensity, respectively, bycolor-representative video signals. The signal source may, for example,be part of a signal receiver of the type illustrated and described in abook entitled Practical Color Television for the Service Industry,revised edition, April 1954, second edition, first printing, publishedby the RCA Service Co. Inc. 7

Also associated with the color kinescope is a scanning deflection yoke20 which may be entirely conventional including two pairs of suitablyplaced coils electrically connected in such manner that, when properlyenergized, electromagnetic fields are produced to efiect both horizontaland vertical angular deflections of the electron beams so as to scan therectangular raster.

Energization of the deflection coils may be effected by conventionalvertical and horizontal deflection wave generators (not shown) whichfunction to produce substantially sawtooth energy at television verticaland horizontal deflection frequencies so that the fields produced by theyoke 20 are varied in a substantially sawtooth manner.

The beam convergence system of the present invention includes aplurality of electromagnetic field-producing elements indicateddiagrammatically by the yoke structure 22 in Figure 1 and shown moreclearly in Figure 2. The convergence magnet assembly includes themagnets 24, 26 and 28 mounted around the neck 30 of the color kinescopeadjacent to the predeflection paths of the electron beam components. Aswill appear in greater detail hereinafter, each of these magnets islocated relative to one of the electron beam components so as toinfluence its associated beam component to the substantial exclusion ofthe others. It is further to be understood that these magnets are ofsuch character that, when suitably energized, they produce respectivefields which are transverse to the associated beam paths.

Before describing the details of the convergence system of the presentinvention, a brief description will be given of the general manner inwhich the apparatus functions to produce the desired result. Theconvergence magnets 24,, 26 and 28 are energized by unidirectionalenergy, as through permanent magnets or the like, so as toefiect aninitial convergence of the electron beam components at the aperturemasking electrode 14. In order to do this, the unidirectional energy ofthe magnets is effected in such manner that the magnets may beindividually energized in different magnitudes. In effecting thisinitial beam convergence, it is to be understood that the beams may bein any desired one of their dificrent deflected positions. For example,they may be initially converged at the center of the raster to bescanned. Alternatively,

they may be initially converged at one corner of the raster.

The convergence magnets are also dynamically energized by control waveenergy derived from a suitable generator so as to effect a variation inthe magnitude in the transverse fields produced respectively thereby.These field strength variations are in accordance with a predeterminedfunction of the beam deflection. Variation in the strength of the fieldsproduced by the magnets 24, 26 and 28 causes corresponding variations inthe paths of the electron beam components relative to the longitudinalaxis of the tube. Hence, suitable variations are made in the convergenceangles between the various beam components so as to produce the desiredconvergence of the beam components at the masking electrode 13.

For a detailed description of the beam convergence apparatus of theinvention, reference will now be made to Figure 2 of the drawing. Thisfigure shows more clearly the positions of the convergence magnets 24,26 and 28 relative to each other and to the electron beams to which theyare respectively associated. The convergence magnet 24 which isassociated with the electron beam 17 is provided with a core comprisingtwo external pole pieces 32 and 34, each of which is substantiallyL-shaped so that the combination of the two pieces 32 and 34 forms agenerally U-shaped assembly. Each of the pole pieces 32 and 34 isprovided in its face adjacent the corresponding face of other polepieces with a generally arcuate recess. Thus, the pole piece 32 has arecess 32a facing an arcuate recess 34a in the pole piece 34. Rotatablysupported in the recesses of the pole pieces is a cylindrical magnet 36which is magnetized permanently along its diameter. The pole pieces 32and 34 and their associated permanent magnets are mounted so as to forma continuous U-shaped magnetic path which is in close association withthe tube neck 30.

As stated above, the tri-color kinescope 14) illustrated herein by wayof example is of the type having internal pole pieces for improvedefiici'ency of the convergence magnets. Thus, there is illustrated foreach of the magnets 24, 26 and 28 a pair or radially and inwardly extending pole pieces. For example, the magnet 24 is provided with a pairof internal pole pieces 40 and 42 7 associated respectively with theexternal pole pieces 32 and 34. It will be understood that, by suchmeans, the reluctance of the magnetic circuit is considerably decreasedand that the flux distribution of the field produced'between theinternal pole pieces 40 and 42 is considerably improved. While thepresent invention is illustrated in conjunction with a kinescope havinginternal pole pieces, it is to be understood that its principles arealso applicable to other forms of tri-color kinescopes.

- In the interest of completeness of description, it will be noted thatthe external pole pieces of each of the magnets are provided withelectromagnetic windings such as the windings 44 and 46 shown around thepole pieces 32 and 34. Each of the magnets is, therefore, adapted toproduce a field between its associated internal pole pieces 'for movingits associated beam in a radial direction toward or awayfrom thelongitudinal axis of the tube. It will be understood in this connectionthat the static convergence of the beams is efiected by suitable controlof the permanent magnets such as the magnet 36 and that dynamicconvergence is controlled by the wave forms applied to the windings suchas the windings 44 and 46. Since the operation of such convergencecircuits is described in the cited Obert article, no further descriptionthereof is necessary.

Figures 2-5 illustrate in detail a novel arrangement in accordance withthe present invention for supporting the beam convergence magnets inoperative relationship about the neck of the kinescope. Each of theconvergence magnets 24, 26, and 28 is held in a foot member 5% of asuitable plastic insulating material such as nylon plastic. Each of thefoot members 51 Stla and Sit-b is provided with an arcuate inner surfaceadapted to fit around the cylindrical neck 3% of the kinescope. Sinceall of the foot members 5 Ella and Silk are identical to each other, thedetailed description will be limited to one of the members. The footmember 5d having an arcuate inner surface is further provided with apair of spaced apertures 54 and 56 for the reception of the legsof the"bshaped external'pele pieces 32 and 34-; respectively. The apertures 54and 56 are of suificient dimensions to accommodate the external poles 32and 34- snugly. in order to prevent the pole pieces, which may be madeof ferrite, for example, from abrading the glass neck 30, the aperturesterminate at the inner surface 52 of the foot member in laterally andinwardly extending flanges or webs 56, as shown more clearly in theenlarged, sectional view of Figure 5. Thus, the pole pieces 32 and areprevented by the webs from contacting the neck of the kinescope. Sinceeach of the webs may be formed of 0.010" thickness, the resultantspacing ofthe pole pieces from the internal pole pieces is so slightthat substantially no undesirable etfect on the magnetic circuit isproduced.

The foot members 5%, 5th: and 5% form, as shown in Figure 2, the sidesof an equilateral triangle circumscribing a circle defined by thearcuate inner surface 52 and corresponding to the outer surface of theneck 30 of the kinescope. The foot member St as shown in Figure 3, isbifurcated to provide a pair of slide portions 53 and 6b which areslidably received in guideways in the form of recesses which are formedin the adjacent end of the foot member 5%. Similarly, the end of thefoot member Stl, remote from its bifurcated end, is provided withguideways 62 and 64 which slidably receive the slides and of the footmember Eda.

It will be understood, therefore, that each foot memher is identical toeach of the other foot members. Further, the foot members 55 56a and5d!) are slidably interfitted with the adjacent foot members to form theabove-described equilateral triangle. It is important to note that, asshown in the drawing, the upper surface of the slides 53 and so whichsurfaces, are designated by the same reference numerals bearing theprime (7) nota tion, are guided by the under surface58" and 60 of theflange which defines the guideways 62 and s4. As may be seen from Figure2, the plane along which the surfaces 53' and 5% meet is a planeparallel to plane drawn tangent to the circle formed by the arcuateinner surfaces of the foot members at the junction of the two footmembers in question. This fact is of importance for reasons to be notedhereinafter.

The foot members 51), 59a and Stlb, which may be readily formed by asimple molding operation, are further provided with apertures 66 and 68at their opposite ends. Thus, when the foot members are assembled as inFigure 2, the aperture 68 formed in the end of the foot member 50 is inalignment with the aperture 66 in the adjacent end of the foot member5%. With the foot members assembled, therefore, each apex of theequilateral triangle has a continuous aperture therethrough, as shown bythe continuous aperture defined by the holes 66 and 63 shown in Figure2. These apertures accommodate spring means which serve to exert tensilepressure upon the corners of the triangle to maintain the foot membersin a contracted condition. in the form of the invention shown in Figures25, such spring means take the form of coil tension springs '79. Eachspring '70 may, as shown in Figures 2 and 3, be provided with two coilportions formed from the same length of spring wire. Each of the springs7lpasses through the cooperating, aligned apertures 66,58 located at oneof the apices of the triangular assembly of foot members and servesadditionally to hold the external magnet pole pieces securely in placein their apertures 54- and 56.

Specifically, a bracket 72 of phosphor-bronze or other suitablenon-magnetic material is provided for each pair of pole pieces 32 and34. The bracket 72, shown more clearly in Figure 4, hasdownwardly-extending flanges 76 along its longitudinal edges to form achannel for the reception of pole pieces 32 and 34. The channel 72 isadditionally provided with a pair of downwardly-bent spring ears 78which, for simplicity of construction, may

be struck out from the ends of the bracket, leaving the apertures 3tmagnetic pole pieces 32 and 34 to urge the pole pieces against thecylindrical magnet 36 thereby securing its three members in their properrelationship. In order to secure the permanent magnet 36 frictionallybetween pole pieces 32 and 3 2, a bent spring wire 82 is booked at itsends under the spring cars 73 and urges against an annular groove 84- inthe shaft of the magnet 36. The springs Tllwhich may also be formed ofphosphor-bronze, for example, are hooked at their opposite ends toengage the apertures in the brackets '72.

In this manner, the springs 70 serve to secure the various elements ofthe convergence magnet assembly into a unitary mount, in which thebrackets '72 are urged toward their respective foot members and the footmerrbers are resiliently urged into tighter contact with each other.Since, in the specific tri-color kinescope described herein, the severalbeam components 17, 18 and l?- are equi-spaced about the longitudinalaxis of the kinescope, it will be understood that each of the three footmembers subtends an arc of substantially so that the external magnetsare maintained with spacings therebetween of 120. By virtue of theequi-angular spacing of the magnets 24, 26 and 28, the external polepieces of the magnets are maintained in proper physical location withrespect to the internal pole pieces of the kinescope to Provide thedesired low reluctance magnetic path.

It will further be recognized from the foregoing that the convergencemagnet mount of the present invention may be readily expanded to fitover the enlarged socket end 30a of the kinescope and, moreover, thatthe triangular mount, by reason of equal spring pressures on the footmembers remains in the desired equilateral configuration. This latteraction stems additionally from the fact that the cooperating surfaces58' and 58" of the slides and guideways formed in the foot members areparallel to planes drawn tangent to the neck of the kinescope at thelocation of the apices of the assembly. Stated otherwise, the tangentialguideways 58 and 6% permit the foot members to move only radially. Thus,regardless of the extent to which the foot members are pulled apart, asto accommodate larger neck diameters, the magnets carried by the footmembers retain their equiangular spacing. Moreover, the magnets remainperpendicular to the axis of the kinescope and concentric with respectthereto. Since the foot members are of appreciable axial length (e. g.,and since the springs exert equal pressures on the foot members, themount in its entirety remains perpendicular to the longitudinal axis ofthe tube.

As shown in Figure 6, the bifurcated end of the foot member 50 may beformed such that its slide portion has parallel surfaces 58, in whichevent the cooperating surfaces 53 of the guideway 58 would also beparallel. The tapered construction of the guide members shown in Figures2 and 3 may be employed for simplicity of the molding operation. Theparallel configuration of Figure 6, however, affords additionalinsurance against non- The spring ears '78 clampingly engage the" thoseelements of Figure 7 corresponding'to the parts of Figure 2 aredesignated by the same reference characters. In the form of theinvention shown in Figure 7, the elongated coil springs are replaced byC-shaped tension springs 90, arranged as shown with the ends of the Usengaging apertures 92 and 94 formed in the foot members. The 10 externalpole pieces are held in place by means of spring members in the form ofneoprene bands 96 whose ends are hooked on to lugs 98 which extend fromthe foot member, as shown.

The form of the invention shown in Figure 7 is particularly adapted foruse in arrangements wherein the ex- 'ternal pole pieces are continuoushoreshoes, that is, with each convergence magnet having a continuousU-shaped core instead of one made of two L-shaped cores. With acontinuous horseshoe core such as the core 100, the static convergencemay be eifected in a known manner through the use of suitable directcurrent windings associated with the magnets. The core 100 has a roundedbright portion .for increased strength. 7 Having thus described myinvention, what I claim as t new and desire to secure by Letters Patentis:

1. Electromagnetic convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member foreach of said magnets, said foot members being arranged around such tubeand having mating means at their extremities for slidably engaging theextremities of adjacent foot members, said' mating means being arrangedto permit substantially only radial movement of said foot members' 2.Electromagnetic convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member forat) each of said magnets, each foot member having a slide portion at oneextremity and a guideway at its other extremity, said foot members beingequilaterally disposed and arranged so that the slide portion of eachfoot member slidably engages the guideway of the adjacent foot member. V

3. Electromagnet convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member foreach of said magnets, each foot member having a slide portion at oneextremity and a guideway at its other extremity, said foot members beingarranged so that the .slide portion of each foot member slidably engagesthe guideway of the adjacent foot membenand means for resiliently urgingsaid foot members inwardly toward the center of such polygon.

4. Electromagnetic convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member foreach of said magnets, each foot member having a slide portion at oneextremity and a guideway at its other extremity, said foot members beingarranged so that the 'slide portion of each foot member slidably engagesthe guideway of the adjacent foot member, said slide portions andguideways having cooperating surfaces which are parallel to planestangent to a circle circumscribed by such foot members.

5. Electromagnetic convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member foreach of said magnets, each foot member having a slide portion at oneextremity and a guideway at its other extremity, said foot members beingarranged along the sides of an equilateral polygon in which the slideportion of each foot member slidably engages the guideway of theadjacent foot member, said slide portions and guideways havingcooperating surfaces which are parallel to planes tangent to a circlecircumscribed by such polygon, and spring means cooperating with theextremities of adjacent foot members for urging said foot membersinwardly toward the center of such polygon. V

6. Electromagnetic convergence apparatus for a cathode ray tube, whichapparatus comprises: a plurality of magnets and means for holding saidmagnets in spaced relationship, said means comprising a foot member foreach of said magnets, each foot member having a slide portion at oneextremity and a guideway at its other extremity, said foot members beingarranged along the sides of an equilateral triangle in which the slideportion of each foot member slidably engages the guideway of theadjacent foot member, said slide portions and guideways havingcooperating surfaces which are parallel to planes tangent to a circlecircumscribed by such triangle.

References Cited in the file of this patent UNITED STATES PATENTS2,440,403 Jackson Apr. 27, 1948 2,749,486 Gould June 5, 1956 2,766,393Casey Oct. 9, 1956 2,791,709 Landes et a1. May 7, 1957

